This invention relates to an apparatus and method for binding media sheets. More particularly, the invention relates to an apparatus and method for producing a bound document from a plurality of media sheets using imaging material as a binding agent.
Current devices and methods for printing and binding media sheets involve printing the desired document on a plurality of media sheets, assembling the media sheets into a stack, and separately stapling, clamping, gluing and/or sewing the stack. In addition to imaging material used to print the document, each of these binding methods require separate binding materials, increasing the cost and complexity of binding. Techniques for binding media sheets using a common printing and binding material are known in the art. These techniques generally involve applying imaging material such as toner to defined binding regions on multiple sheets, assembling the media sheets into a stack, and reactivating the imaging material, causing the media sheets to adhere to one another.
These known devices and methods, however, can consume significantly more time than producing an unbound document. Each involves printing the entire or a substantial portion of the desired document, then assembling and aligning the media sheets into a stack in preparation to be bound. Binding the stack of media sheets also entails applying sufficient heat to the binding region to reactivate the imaging material throughout multiple sheets or throughout the entire stack. Consequently, the thickness of the bound document is limited by the device""s ability to adequately heat the binding regions throughout multiple sheets or the stack without damaging the media sheets. In some instance it is desirable to simultaneously bind a stack of media sheets. However, as the binding regions of the sheets in the stack are heated, the thickness of the stack decreases. Failing to compensate for this decrease produces sub-optimal binding conditions.
The present invention is directed to a device for binding a stack of media sheets using imaging material as the binding agent. In one embodiment, the binding device includes a tray for supporting the stack and a heated platen or some other type of imaging material activator near the tray. A press coupled to the activator is operative between a first position in which the activator is separated from the stack to a second position in which the activator contacts and compresses the stack at the binding region. A spring or other biasing mechanism operatively connected between the press and the activator biases the activator against the stack when the press is in the second position. The biasing mechanism allows pressure to be maintained on the stack to reactivate the imaging material without continuing to power the press down against the stack even as the stack shrinks under the reactivating pressure. Hence, power can be diverted if necessary or desirable from the press to activator to reduce the overall power consumption of the binding device.